Method and apparatus for making ceramic shapes



E. LUX

Jan. 30, 1934.

METHOD AND APPARATUS FOR MAKING CERAMIC SHAPES Filed A1121. 10, 1931Patented Jan. 30, 1934 UNITED STATES PATENT OFFICE- METHOD AND APPARATUSFOR MAKING A CERAIVIIC SHAPES tion of Delaware Application August 10,

1931, Serial No. 556,217,

and in Germany August 11, 1930 6 Claims.

The invention relates to the making of ceramic shapes for themanufacture of refractories and the like and especially for thoseprocesses by which a body of reduced refractory material and a bond isprepared with a small addition of a defiocculating agent and water inorder to convert the mass by mechanical agitation for instance inshakers, into a temporarily plastical up to a semi-fluid stage, wherebyit 'is to be understood that a semi-fluid mass is somewhat more viscousthan the masses employed hitherto in the ordinary casting processes.

According to the above processes the vibration of the moulding mass hasbeen carried out as far under normal air pressure. In this manner thereare obtained, however, comparatively porous shapes, the moulding masscontaining a certain quantity of air being enclosed by the highlyviscous bond and held fastly same in the form of large bubbles.

Now, the principal objects of the invention are improvements of theabove mentioned process by means of which the disadvantages hitherto metwith are avoided and consequently shapes of a higher density than up tothe present are obtained.

The process according to the invention consists principally therein thatfrom a reduced refractory material and a bond preferably containing clayor consisting of clay alone together with a deflocculating agent a massis mixed with so much water that the mass on the one hand is in asomewhat crumbly state after the mixing has been effected and on theother hand contains suf- 85 ficient moisture in order to be converted onbeing shaken or subjected to vibrations into a plastic up to/or asemifiuid condition, whereupon said mass is filled into a mouldcorresponding to the surface of the shapes to be made, then the air 49pressure in the mould is reduced and afterwards the mass is subjected tomechanical vibrations until the mass in the mould is converted as awhole into a doughly plastical or semifiuid state and the cavities ofthe mould are fully occupied by the mass, whereupon finally themechanical vibrations are stopped; the shapes thereupon rapidly set andare taken out of the mould. Further, according to the invention, thecavity of the mould is kept under lower air pressure not only before,but also entirely or partly during the vibrating of the mass. The vitalpoint is, however, that the air pressure in the mould containing themass is reduced whilst the mass is entirely u in the crumbly state, inother words, before any part of the mass is converted into a doughyplastical or semifiuid state.

In the case of the process according to the invention, as hereinabovedescribed, it is in general necessary to employ a moulding mass with acontent of water as high as for instance 8 percent. Although this watercontent is lower than in the case of ordinary casting process it isnevertheless sometimes undesirably high.

A further object of the invention are improvements of the alreadydescribed known process for the making of ceramic shapes for the purposeof rendering possible a considerable reduction in the water content ofthe moulding mass. To this end, according to the invention, the mouldingmass is subjected to compressions, preferably with a heavy or a springweighted stamp, during the vibration process. This method permits ofbringing the addition of water to the moulding mass down to about 5%.

A further object of the invention is a machine for carrying out theprocess according to the invention for the manufacture of shapes formaking refractories and the like.

With these and other objects of the invention in view, I will nowdescribed a machine for carrying out the object of the process accordingto this invention which is shown on the drawing in a side-view andpartly in a vertical section.

In the case of the machine, as shown on the drawing, a mould 2 serves totake the mass 1 and is arranged on the table 5 of a vibrator 6, which inthe customary manner, is provided with a stamp driven by compressed airsimilarly to a known shaking contrivance. The mould 2 is fixed, by theinsertion of a packing 2:1 and by means of clamps 3, and screws 4, tothe table 5. The vibrator is fitted up in the frame 7 of the mouldingmachine on one side of which a tube 8 is arranged for connecting up thevibrator with a compressed air pipe.

On the frame of the machine further, there is fixed by means of screws10, on the side close to the vibration table 5, an arm 9 extendingupwards which has a vertical guide 11. On this guide 11 there is agliding slide 12 which can be moved vertically and is provided on oneside with two vertically spaced supporting arms 13 and 14, arrangedabove the mould 2. The shaft 15 of a stamp serving to compress themoulding mass into the form, is carried in the arms 13, 14, so as to bemovable in a vertical direction.

On the shaft 15 there is fixed by means of the screw 16 an adjustablering 17 which serves to support the shaft of the stamp on the lowerslide arm 14. Between this supporting ring 17 and the lower side of theupper slide arm 13 there is arranged a pressure spring 18 by means ofwhich the stamp 15 is held in such a position that, when the shaft ofthe stamp is drawn off the supporting ring 17 lies against the lowerslide arm 14. The slide 12 is provided on the other side with a set ofteeth 19. With the teeth 19 of the slide 12, a pinion 20 engages whichis fixed to an axis 22 arranged on the supporting arm 9 and which isworked by the hand wheel 21.

During the formation of the shape inside the mould, the cavity is closedabove by a cover 23 which is fastened together with a packing 24 on theupper part of the mould by means of turnable threaded bolts 25 and nuts26. The cover 23 has an opening 27 for the lower end of the shaft stamp15, whereby a customary stuffing box 28 serves to render the joint tightbetween the shaft of the stamp and the cover. The shaft 15 carriesfinally in the interior of the mould cover a stamp plate 29 whichcorresponds approximately to the section of the mould cavity and is sofitted over the mould that it can be moved into the mould.

On the mould cover 23 there are, moreover, fitted two tubes 32, 33controlled by the cooks 30, 31 of which the tube 32 serves to connect upwith the fiexible hose 34 of a suction air pipe line and the other tube33 for the connecting up the interior of the mould with the outside air.

The working of the contrivance shown in the drawing for the making of ashape proceeds about as follows:

When the vibration contrivance 6 is not in action and the cover 23 hasbeen taken off, which in this case is lifted upwards by means of theslide 12 from off the mould, a quantity of a moulding mass consisting ofreduced refractory material and a bond with an addition of adeflocculating agent and water which corresponds to the weight of theshapes to be produced, and which has been mixed together in a mixer, notshown in the drawing, is filled into the mould. Thereupon, the cover 23by moving the slide 12 downwardly by means of the hand wheel 21 is setonto the mould and then the fixing screws 26 are screwed down so thatthe joints between the cover and the mould are closed absolutelyair-tight by means of the packing 24. Now, the shut-off cock 30 of thesuction air pipe line is opened and the interior of the mould isevacuated. As soon as the air has been expelled from the form to thedesired degree which can be determined without trouble by the pressurein dicator fitted in the suction pipe line, then the slide 12 by meansof the hand wheel 21 is moved further downwards so that the stamp 29lies firmly on the upper side of the moulding mass and the pressurespring 18 is compressed to an extent which corresponds to the desireddegree of compression of the mass inside the mould. Now the vibrator 6is put into action and the mass inside the mould is vibrated so longuntil the mass has the desired condition. In this connection it is undercertain circumstances necessary to move down still more the stamp slide12 to such an extent that the mass to be moulded can be held whilstbeing vibrated under a uniform pressure by means of the action of thespring 18.

It may be remarked that the spring 18, of course, can be replaced by aweight fixed on the shaft 15.

when using the described machine for carrying out the process accordingto the invention without subjecting the moulding mass to compressionduring the vibration process, the compression remains then out ofaction, i. e. the slide 12 is not moved downwards after the cover 23 isplaced on the mould 2. In order to assure a smooth surface of the shape,however, it may be advisable to merely allow the stamp plate to restloosely on the moulding mass, this being attained by loosening the screw16 of the adjustable ring 17.

Needless to say the cover of the mould as shown may be replaced, in thecase dealt with in the foregoing paragraph, by an ordinary cover notprovided with a stamp.

The preparation of the moulding mass serving to carry out the processaccording to the invention is effected essentially to conform with thefollowing principles:

Example I A mixture is prepared from:

A.--Rejractory material 190 kilos of a highly burnt clay (chamotte)reduced to 5 mm. maximum grain size.

B.Bond

5 kilos of ball clay 5 kilos of china clay, both finely groundC.--Deflocculating agents 0.3 kilos of humic acid (called Kesselerbraun) 0.02 kilo of sodium carbonate 0.01 kilo of sodium silicate.

D.--Water 10 liters After mixing and preparing in the ordinary manner,the mass is filled into a mould, the interior of which is then evacuatedwhereupon the mass in the mould is vibrated and simultaneously pressed,as described hereinabove.

50 kilos of sillimanite flour (sieve No. 100) 20 kilos of ball clay.

C.Deflocculating agent 0.6 kilo of tannic acid 1 liter of a solution ofammonia (25%).

D .-Water 16 liters After mixing and preparing in an ordinary mixer,this mass may be subjected to the process described but without exertingany pressure, as it is rendered fluid enough by the vibrating to fillout the mould completely.

In this case it may be advantageous to line the mould walls with amaterial suitable to suck up water such as for instance sheet rock.

It may be understood, that the process is not confined to the abovementioned mixtures, but there may be used any other refractory materialsbeing reduced to a proper grain size, such as corundum spinell,magnesite, quartzite, silicon carbide or others and the bonding materialmay consist of the finey ground part of the refractory material and mayor may not contain clay. As deflocculating agents may be used any ofthese substances hitherto known from the casting processes.

The invention as hereinabove set forth is embodied in a particular form,but may be variously embodied within the scope of the claims hereinaftermade.

I claim:

1. A machine for making ceramic shapes comprising, a vibrating machine,a mould arranged on the working member of the vibrating machine, a guidearranged vertically above the mould, a slide gliding on said guide, acover for closing up the interior of the mould and attached to the saidslide, and means for evacuating the interior of the mould.

2. A machine for making ceramic shapes comprising, a vibrating machine,a mould arranged.

on the working member of the vibrating machine, a guide arrangedvertically above the mould, a slide gliding on said guide, a stampadapted to compress the moulding mass held in the mould on the workingmember of a vibrating machine, means for closing up the interior of themould, means for pressing the stamp on the moulding mass held in themould, and means for evacuating the interior of the mould.

3. A machine for making ceramic shapes comprising, a vibrating machine,a mould arranged on the working member of the vibrating machine, a stampadapted to compress the mass held in the mould, a cover adapted tocompletely close up the interior of the mould, a vertical guide arrangedabove the mould, a slide glidable thereon, said stamp having a verticalshaft passing through a hole in said cover and attached glidably to saidslide, and means for evacuating the interior of the mould.

a wiv 4. A machine for making ceramic shapes comprising, a vibratingmachine, a mould arranged on the working member of the vibratingmachine, a stamp adapted to compress the mass held in the mould, a coveradapted to completely close up the interior of the mould, a verticalguide arranged above the mould, a slide glidable thereon, saidstamphaving a vertical shaft passin: through a hole in said cover andattached glidably to said slide, a ring attached to the stamp shaft, aspring between said slide and the ring so as to press the stampdownwards elastically, and means for evacuating the interior of themould.

5. The method of making ceramic shapes which comprises: placing themixture to be moulded, while in a somewhat crumbly or nonfluid state butcontaining suflicient moisture or liquid, in mould; subjecting themixture to mechanical vibration until the mass mixture is converted as awhole into a doughy plastical or semi-fluid state; and evacuating air orgas from the mixture while in the crumbly or non-fluid state in themould and before it is subjected to said vibration.

6. The method of making ceramic shapes which comprises: placing themixture to be moulded, while in a somewhat crumbly or nonfluid state butcontaining sufiicient moisture or liquid, in mould; subjecting themixture to mechanical vibration until the mass mixture is converted as awhole into a doughy plastical or semi-fluid state; and evacuating air orgas from the mixture both while in the crumbly or nonfluid state in themould and before it is subjected to said vibration and also during saidvibration of the mixture.

ELISABETH LUX.

